I started looking at it and wrote what I know about it on the wiki, but I haven't found out much yet, especially not how it actually makes CEZ's flags wave. Just look at map11 in SRB2DB, it doesn't seem all too complicated.

You don't need to know any coding language to grasp the basics of linedef specials in the source code. In most cases, it's rather easy to decipher. My main problem is that I don't quite know where to look for this. It's probably defined in "p_polyobj.c", but where?